1. Field of the Invention
This invention relates to a pipe joint.
2. Description of the Related Art
A conventional pipe joint to connect pipes of synthetic resin for water supply is provided with a joint main body having an insertion cylinder portion inserted to an end portion of a pipe, a clamp ring having a slit to fasten the end portion of the pipe inserted to the insertion cylinder portion by elastic fastening force, and a diameter-expansion piece releasably held within the slit as to expand a fastening ring against the elastic force of the clamp ring and released when the pipe is inserted (refer to Japanese patent provisional publication No. 2002-31282).
In this conventional pipe joint, a defective work, in which the insertion of the pipe is not enough despite the release of the diameter-expansion piece, may be conducted. And, the insertion depth of the pipe may be excessively small, resistance against drawing may be made weak, and the insertion depth can not be regulated because the diameter-expansion piece is held by inner end portion in an axis direction of the clamp ring. And, the clamp ring may become tapered as the inner diameter of the outer end portion (to which the pipe is inserted) in the axis direction is small because the diameter-expansion piece is held by inner end portion in an axis direction of the clamp ring. This makes holding work (insertion work) of the diameter-expansion piece difficult because the insertion of the end portion of the pipe is hard to conduct, and the clamp ring is required to be preliminarily expanded large.
It is therefore an object of the present invention to provide a pipe joint with which pipes are easily connected, misconnection of the piping is certainly checked, and defective work can be prevented beforehand. Further, it is also an object to provide a pipe joint with which the clamp ring is expanded uniformly in the axis direction (as not to be tapered) and the pipe is smoothly inserted.